1. Field of the Invention
The present invention relates to car navigation, and more particularly, to a method and apparatus for three-dimensionally transforming two-dimensional linear data in accordance with three-dimensional topography data in real time and a method and apparatus for three-dimensionally visualizing two-dimensional linear data together with three-dimensional topography data in real time.
2. Description of Related Art
Recently, increase in the number of cars on roads has caused a serious problem of traffic congestion. In order to solve the traffic congestion, there have been developed car navigation systems. The car navigation system has basic functions of tracking a position of a car and displaying the position on a road map. The car navigation system has additional functions of monitoring traffic situation of roads and providing the traffic situation information to drivers.
A well-visualized car navigation system enables the drivers to accurately locate their destination on the road map. In addition, when a car travels at a high speed, a three-dimensionally visualized road map of the car navigation system provides more convenience and safety to a driver than a two-dimensional map. Buildings and geographical features are depicted three-dimensionally on the three-dimensionally visualized road map, so that the driver can perceive them intuitively.
Conventional car navigation systems store two-dimensional linear data and visualize the data two-dimensionally.
There is an approach for three-dimensionally displaying two-dimensional map data with use of perspective as shown in FIG. 1. In this approach, distances or lengths in the two-dimensional linear data are differently displayed on the map according to a user's viewing point to provide perspective to the map. For example, the same lengths b1 and b2 on a plan S are displayed with different lengths d1 and d2 on a plan P according to the distances between the user's viewing point B and the lengths d1 and d2. In the approach, the two-dimensional linear data cannot be transformed into three-dimensional topography data with reality. In addition, in the approach, road data which changes according to the three-dimensional topography data is not considered.
Conventional navigation systems cannot obtain or store three-dimensional data due to their map data collecting methods. In general, the map data is collected with airplane photography, and two-dimensional map is obtained from the map data.
National Geographic Information Institute collecting and managing topography data transforms the topography data into three-dimensional topography data. However, the three-dimensional topography data does not include three-dimensional data of buildings, roads, and so on. Therefore, in order to completely visualize all geography features on the map, it is necessary to a method of three-dimensionally transforming the two-dimensional linear data of the buildings and roads in accordance with three-dimensional-topography data in real time and three-dimensionally visualizing two-dimensional linear data together with three-dimensional topography data in real time.